<template>
  <view>
    <view class="scroll-view-container">
          <!-- 左侧的滚动视图区域 -->
          <scroll-view class="left-scroll-view" scroll-y :style="{height: wh + 'px'}">
         <block v-for="(item, i) in cateList" :key="i">
           <view :class="['left-scroll-view-item', i === active ? 'active' : '']" @click="activeChanged(i)">{{item.cat_name}}</view>
         </block>
           
          </scroll-view>
          <!-- 右侧的滚动视图区域 -->
          <scroll-view class="right-scroll-view" scroll-y :style="{height: wh + 'px'}" :scroll-top="scrollTop">
          <view class="cate-lv2" v-for="(item2,i) in cateLevel2" :key='i'>
            <!-- 2级分类 -->
             <view class="cate-lv2-title">{{item2.cat_name}}</view>
             <!-- 3级分类 -->
            <view class="cate-lv3-list">
                 <!-- 三级分类 Item 项 -->
                 <view class="cate-lv3-item" v-for="(item3, i3) in item2.children" :key="i3" @click="gotoGoodsList(item3)">
                   <!-- 图片 -->
                   <image :src="item3.cat_icon"></image>
                   <!-- 文本 -->
                   <text>{{item3.cat_name}}</text>
                 </view>
               </view>
          </view>
          </scroll-view>
        </view>
  </view>
</template>

<script>
  export default {
    data() {
      return {
         // 窗口的可用高度 = 屏幕高度 - navigationBar高度 - tabBar 高度
          active: 0,
        wh:0,
        cateList:[],
        cateLevel2 :[],
        scrollTop:0
      };
    },
     onLoad() {
          // 获取当前手机设备的信息
          const sysInfo = uni.getSystemInfoSync()
          // 为 wh 窗口可用高度动态赋值
          this.wh = sysInfo.windowHeight
         this.getCateList() 
        },
        
        methods:{
         async getCateList(i){
            const {data:res}= await uni.$http.get('/api/public/v1/categories')
            this.cateList=res.message
            this.cateLevel2 =res.message[0].children
          } ,
          // 选中项改变的事件处理函数
          activeChanged(i) {
            this.active = i
            this.cateLevel2 =this.cateList[i].children
            this.scrollTop= this.scrollTop===0?1:0
          },
          gotoGoodsList(item3){
            uni.navigateTo({
              url:'/subpkg/goods_list/goods_list?cid=' + item3.cat_id
            })
          }
        }
  }
</script>

<style lang="scss">
.scroll-view-container {
  display: flex;

  .left-scroll-view {
    width: 120px;

    .left-scroll-view-item {
      line-height: 60px;
      background-color: #f7f7f7;
      text-align: center;
      font-size: 12px;

      // 激活项的样式
      &.active {
        background-color: #ffffff;
        position: relative;

        // 渲染激活项左侧的红色指示边线
        &::before {
          content: ' ';
          display: block;
          width: 3px;
          height: 30px;
          background-color: #c00000;
          position: absolute;
          left: 0;
          top: 50%;
          transform: translateY(-50%);
        }
      }
    }
  }
}
.cate-lv2-title {
  font-size: 12px;
  font-weight: bold;
  text-align: center;
  padding: 15px 0;
}
.cate-lv3-list{
  display: flex;
  flex-wrap: wrap;
  .cate-lv3-item{
    width: 33.33%;
    margin-bottom: 10px;
    display: flex;
    flex-direction: column;
    align-item:center;
    image{
      width: 60px;
      height: 60px;
      text{
        font-size: 12px;
      }
    }
  }
}
</style>
